I'm basing this solely on the dyno on crateenginedepot.com, but it looks like the manifold really picks up the upper RPM range and it doesn't drop of significantly at redline. Do you think this, coupled with I/H/E/TB would be enough to warrant raising the redline and moving to ~310cc injectors. Don't eco's run very high IDC's on the stock injectors with minimal mods anyway?
I'm asking to guage if i need HPT and injectors when i get the mani, or if HPT/injectors can wait for comp stage1.
Well it all depends on the duty cycle the injectors are running at.
But I have heard / read that ecotec injector duty cycles are high stock.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
-MD- LD9 wrote:Well it all depends on the duty cycle the injectors are running at.
But I have heard / read that ecotec injector duty cycles are high stock.
I agree with you - its been especially well documented that head work/cams/higher RPM than stock REQUIRES higher flowing injectors due to >100% IDC.
So I guess my question was twofold:
- Do you think that the HO intake manifold will warrent reving over the stock redline - it looks like the power does not significantly drop off.
- Whether reving to stock redline or ~7k rpm, will the stock injectors need to be upgraded with the HO mani and I/H/E/TB mods?
FYI my reg is upto date...
Well, i orded the manifold conversion kit. I guess I'll slap it on and see how it feels untuned, but a WB and HPT are probably in my future.
Also I just noticed that crateenginedepot's dyno shows a peak hp gain of ~13whp, but the gain at redline is ~25whp!! That's untuned on a cobalt ECU w/ intake and cat-back on both before and after.
I'll post again after installation
not smart.
I thought I covered this in all of my all motor threads in 2006/2007?
the factory ecotec injectors are too small for stock motor. once you try to tune them for a good AFR (around 13.0:1) they hit over 100% duty cycle.
this is again on a STOCK ecotec. stock head, stock block, stock cams. the injectors are too small.
the HO manifold (LE5 manifold) is fine, but without tuning and using larger injectors you're going to run lean. The only advantage you have is the stock eco ECU doesn't go into open loop until very high in the RPM band, meaning that it'll shoot for 14.7:1 AFR pretty much the whole time, but still.. I doubt they're large enough to support the extra airflow... its going to run lean.
how do you think I did this?
lean spot, high rpm, and kR turned off.
get larger injectors, and get HPT before putting that manifold on, that's my suggestion. On a stock engine I was at 107% injector duty cycle with the factory injectors.. and this is at 6200rpm.. way before a higher redline.
I just posted a WTB for injectors in NE as you were typing
I appreciate your pointers and hope to benefit from your experience. I've read all the threads you're refering too, but I thought you logged the static IDC's with the LZM cams and Patriot head? I could be mistaken. Also, the dyno on CED has an AFR plot and its showing low to mid 12's??? I know this was on a cobalt L61, but the injectors should be the same right? What about fuel pressure? Maybe it was inaccurate? In any case, I'm looking for injectors.
And no matter what, im NOT turning off the knock sensor!!
DaFlyinSkwir(LS61) /PJ/ OEM+ wrote:not smart.
I thought I covered this in all of my all motor threads in 2006/2007?
the factory ecotec injectors are too small for stock motor. once you try to tune them for a good AFR (around 13.0:1) they hit over 100% duty cycle.
this is again on a STOCK ecotec. stock head, stock block, stock cams. the injectors are too small.
the HO manifold (LE5 manifold) is fine, but without tuning and using larger injectors you're going to run lean. The only advantage you have is the stock eco ECU doesn't go into open loop until very high in the RPM band, meaning that it'll shoot for 14.7:1 AFR pretty much the whole time, but still.. I doubt they're large enough to support the extra airflow... its going to run lean.
how do you think I did this?
lean spot, high rpm, and kR turned off.
get larger injectors, and get HPT before putting that manifold on, that's my suggestion. On a stock engine I was at 107% injector duty cycle with the factory injectors.. and this is at 6200rpm.. way before a higher redline.
Good info PJ.
Proud member of Jbody of Kentucky ... Click on sig to go!
I have an 04 5 speed coupe that i want to throw this manifold on
if i can scrape the cash together, expect to see a dyno before and after. I have spare injectors to throw in the car too if it needs it.
DaFlyinSkwir(LS61) /PJ/ OEM+ wrote:I have an 04 5 speed coupe that i want to throw this manifold on
if i can scrape the cash together, expect to see a dyno before and after. I have spare injectors to throw in the car too if it needs it.
Crateenginedepot.com has a dyno posted for a basically stock cobalt 2.2 (intake and cat back). I know the ECU is different, but untuned it yielded a peak gain of 13whp and a gain of ~20hp at redline. There was a slight loss (~5whp max) at 3.5-4.5k rpm. They compared the best runs for both manifolds. I'd say this thing is a real treat for higher reving eco's
I would expect similar gains on a TUNED eco cav...I'm hoping anyways!
listening
Lanman31337 -F = fatties = do not want. A little chunk in the junk is ok though.
thats because the cobalt can compensate with the MAF, tuning a cobalt vs tuning a jbody with that manifold will probably yield the same results.
I'd prefer to do real world testing anyway since I'm not trying to sell the manifold.
if I ever get around to it i'll post up the results
well i have some stock LSJ injectors if anyone wants to buy them for this??
RyZ96 wrote:well i have some stock LSJ injectors if anyone wants to buy them for this??
they are too short for the 2003-2005 fuel rail
however they fit on the 2002 fuel rail i'm pretty sure
you are correct
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
DaFlyinSkwir(LS61) /PJ/ OEM+ wrote:RyZ96 wrote:well i have some stock LSJ injectors if anyone wants to buy them for this??
they are too short for the 2003-2005 fuel rail
however they fit on the 2002 fuel rail i'm pretty sure
Is the return system on the 03 the same as the 02, I have an early 03.
==============================================================
Yes, noob, the search button is for you...
you gotta replace the hardlines associated with the proper rail. in other words, everything up to the black hoses with special quick connect fittings for the fuel rail needs to be for the appropriate year.
02 hardlines for an 02 rail
03-05 hardlines for an 03-05 rail
the hoses that connect both are the same
the only thing you need to make sure you have is the plastic injector spacers, i'm not sure they have them on the 2002 engines.. you'll need them for the LSJ injectors to fit the L61
just fyi everyone here
I did an HPT log of the fuel injector duty cycle on my stock 2004 eco 5 speed.
at WOT they're 87% duty cycle, and I can guarantee this is at a BAD AFR.. ie, not ideal.. and they're already maxed out.
Good info man....if i can pick your brain for a second, what would be a good injector to swap to for a mild NA build.
Im considering this manifold and perhaps a set of cams.
its looking like stock should be 310cc/min for basic AFR tuning and even a mild build should be 440cc/min. Jeez, time for new injectors...off of the showroom floor.
i had the skwirl on 440cc I think my highest duty cycle was around 55%
but for a mild to extreme build, 440cc are probably the easiest to find (ford green tops) and give plenty of headroom.
although when tuning with HPT, I did have some stalling issues and low rpm drivability problems which I'm sure stemmed from the injector constant calculation
The calculation of injector duty cycle has nothing to do with the "injector constant" correct? IDC is based on injector pulsewidth so an incorrect constant would not skew the IDC?
Would increasing the static fuel pressure be of any use? If I understand the ECU correctly, it would pull pulsewidth in closed loop to attain 14.7:1 AFR, but since power enrichment is independent of the sensors, it would run proportionally rich. So the biggest issue is when does PE engage?
I'm going to admit that I went against advice and installed the HO mani w/o tuning just to see how it felt. On the first start up it hunted for idle for quite a whle, but it did evenutally settle in at ~800rpm. I did drill out the throttle body adapter to accomodate idle air control.
Part throttle feels excellent - very strong; from 2500-3500 its just a rush believe it or not. After about 3500rpm it's dead as a door nail. Same thing if I floor it. My interpretation, as well as the forecast from other members, is that its lean and I'm out of injector. The HO mani is off until I can tune. I wanted to learn the hard way. After I get a wideband i may throw it back on and see how bad it really is before tuning. I know its kinda a dangerous game, but i didnt do WOT runs to redline every chance i got.
Thanks for the help everyone!
oldskool wrote:The calculation of injector duty cycle has nothing to do with the "injector constant" correct? IDC is based on injector pulsewidth so an incorrect constant would not skew the IDC?
Would increasing the static fuel pressure be of any use? If I understand the ECU correctly, it would pull pulsewidth in closed loop to attain 14.7:1 AFR, but since power enrichment is independent of the sensors, it would run proportionally rich. So the biggest issue is when does PE engage?
I'm going to admit that I went against advice and installed the HO mani w/o tuning just to see how it felt. On the first start up it hunted for idle for quite a whle, but it did evenutally settle in at ~800rpm. I did drill out the throttle body adapter to accomodate idle air control.
Part throttle feels excellent - very strong; from 2500-3500 its just a rush believe it or not. After about 3500rpm it's dead as a door nail. Same thing if I floor it. My interpretation, as well as the forecast from other members, is that its lean and I'm out of injector. The HO mani is off until I can tune. I wanted to learn the hard way. After I get a wideband i may throw it back on and see how bad it really is before tuning. I know its kinda a dangerous game, but i didnt do WOT runs to redline every chance i got.
Thanks for the help everyone!
I believe you are right about the IDC,
the manifold installed without tuning in all honesty won't blow up your car because you still have kR engaged, but I'm willing to bet its pulling maximum allowable timing retard at WOT.. which, coupled with running lean will pull some big time power.
when you try to tune for a better AFR the injectors are going to be maxed out right away (keep in mind, the ecu can NOT 'adapt' to flow changes so its still running the program optimized for the factory intake manifold and won't know any better until its HPT'd)
but get injectors on there and a decent tune and you will be more than happy.
